Leap2A XSLT rendering and validation

Still to be implemented: leap2:activetime formatting; anything I've forgotten.

Leap2A (XML) file
OR URL of Leap2A XML
OR Upload a Leap2A XML or .zip file
XSLT file
Stylesheet (optional)
Resolve CURIES? (This option pre-processes the Leap2a XML to resolve CURIES in attributes and content.)